The invention relates in general to a method and apparatus for characterizing gastrointestinal sounds and in particular to a method and apparatus employing a microphone array attachable to a patient's body for collecting sounds from multiple sources in the body and a computer system for receiving digitized gastrointestinal sound signals and determining the spectra and duration of the sounds and characterizing states of the gastrointestinal tract on the basis of the spectrum and duration.
It has been known in the past to employ electronic analysis of sounds from the gastrointestinal tract as an adjunct to the physician auscultating the gastrointestinal tract in an attempt to determine quickly and with a minimum of diagnostic equipment the condition of the patient. In the past, for instance, as disclosed in U.S. Pat. No. 5,301,679, a method and system was provided for providing diagnostic information for various diseases including diseases of the gastrointestinal tract by capturing body sounds in a microphone placed on the body surface or inserted orally or rectally into the gastrointestinal tract. The spectrum analyzer used a real time audio one-third octave technique using a plurality of analog filters and a peak detector provide a log calculation of envelope amplitudes. Other systems also used microphones sensitive to specific frequency ranges and are exemplified by Dalle, et al. "Computer Analysis In Bowel Sounds," Computers in Biology and Medicine February 1975 4(3-4) pp. 247-254; Sugrue et al. , "Computerized Phonoenterography: The Clinical Investigation of the New System," Journal of Clinical Gastroenterology, Vol. 18, No. 2, 1994, pp. 139-144; Poynard, et al., "Qu'attendre des systemes experts pour le diagnostic des troubles fonctionnes intestinaux," Gastroenterology Clinical Biology, 1990, pp. 45C-48C. Also of interest are U.S. Pat. Nos. 1,165,417; 5,010,889; 4,991,581; 4,792,145. Unfortunately, none of the systems relate to using specific morphological filtering an event characterization of the type which might be able to identify ileus or small bowel obstruction or the like. The prior systems seem to have suffered from the inability to cope with relatively irregular sounds and irregular signals and to pick events of detail from the signal. Many of the systems used averaging techniques on the raw signal, which would tend to obscure the event of interest in noise or other unwanted portions of the signal and thus actually work against the diagnostician attempting to characterize genuine gastrointestinal sounds as opposed to other sounds coming form the body. Thus, it would appear that despite the use of sophisticated spectral techniques and the like the prior art, having been unable to identify events, appeared to operate on relatively noisy data from which it would be difficult to extract meaningful conclusions. Accordingly, what is needed is a system which can quickly and easily identify such conditions.